(defun submit ( lst)
  ;;this submit can skip nil 
  (if (>= (length lst) 2 )
      (let ((x (car lst)))
	(if (eql x nil)
	    (submit  (cdr lst ))
	    (funcall #'+  x (submit  (cdr lst)))))
      (let ((y (car lst)))
	(if (eql y nil )
	    0
	    (car lst)))))